Device for magnetic control of a discharge



\ Aung@ 275, E945 H. M. STRQBEL.

DEVICE FOR MAGNETIC CONTROL OF A DISCHARGE Filed July 7, 1945 IN1/EN TOR. Hah/,mv /145' 5f/zaga TT ORNE Y Patenied ug. 7, 1945 UNITED sTATEs vPATENTV OFFICE DEVICE FOB HAGNETI() UGNTBOL l' A DISCHARGE Howard M. Strobel, New York, N. Y.

Application July 7, 1943, Serial No. 493,717

(ci. zoo- 141) 12 Claims.

This invention relates to a device for magnetic controllo! a discharge and particularly to one in which an electric current carried between two electrodes by conduction of gaseous ions is modii'ied by the use of a magnetic field which denects the discharge against the surface of a deionizing structure and its object is to improve sucha deionizing structure so that it will more effectively break up n magnetically deflected discharge. ln my Patent No. 2,261,507, issued November i941, l have disclosed s. device in which the idea was incorporated in a discharge tube which could be operated at reduced pressures and in my application Serial No. 460.31%. iiled June 27, i943., I disclosed o. device which could be operated in the open air or at atmospheric pressure. This application is a continuation in part of the aforesaid cc-pending application.

increasing the lengths and resistance of a discharge path by magnetic deflection and crushing the ionized discharge against a collector plate by stronger magnetic holds have been used, but it has been overlooked that resulting electrostatic forces oi attraction, due to the positive ion space charge created on the stopping surface, oppose or balance the magnetically derived deflectlng forces exerted upon the moving electrons, and since these electrostatic forces increase substantially in direct proportion to the strength of the applied magnetic field, no appreciable gain in disruptive capacity is obtained. My purpose is to provide an improved device whereof the surface against which a discharge is magnetically deiiected is constructed to form trapping ele ments which shield the magnetically deflected eiectro.. s from those electrostatic fields which previously iirnited the effectiveness of magnetic control oi c discharge.

These and other objects of the invention will appear in the following specication in which I will describe some embodiments of the invention. the novel features ci whichwill be set forth in appended claims.

Referring to the drawing: Figure l is a diagram showing the general relationship between arc-splitting pins or elements which embody my invention and an are discharge such as is caused by the opening of a circuit breaker. Fig. 2 is an enlarged cross section o! a clonventional arc splitting pin and the electro-static field built up when an arc discharge is deected against it.

Pig. 3 is an enlarged sectional view of one of the pins shown in Fic. l.

Fig. 4 is a side view of the pin shown in Fig. 3.

Fig. 5 is a perspective view on a larger scale of an arc splitting pin provided with a trapping device according to the present invention. l

Fig. 6 is a perspective view showing the construction of the conductive shielded pockets within the pin shown in Fig. 5 which is hollowed out to receive them. y

Fig. 'i is a perspective view of an arc splitting pin of modified construction embodying the invention, in which the deionizing surfaces of the trapping member are formed in a simple mane Fig. 8 is a side elevation of a conventional arrangement oi'; arc splitting pins in a magnetic blow-out arc chute, used for interrupting an electrical arc discharge through an ionized medium.

lin Fig. l, ilo, and H2 designate arc-splitting pins which have been modified in accordance with my invention to include within them a de- H5, -.||8A and ill, toform pockets, |20a, |2017, Iliilc,l

and |d (Figs. 3 und 4). A metal shielding lattice or screen H8 is shown screening the pockets. H9 is a vent and |2| and |22 designate movable contacts of a circuit breaker which on separating form an arc discharge between them.

Let it be assumed that an electrical discharge has been created between the electrode contacts i2! and |22 and that there is no transverse magnetic field applied. It contact |2| is negative and contact |22 positive. a positive ion at |30 or |3| would be drawn towards the negtaive contact |2| and negatively charged particles would be drawn toward the positive contact |22. Ii' the arc discharge path is deflected upwards by purely mechanical forces, such as by an air blast, the positively and negatively charged particles will be more or less uniformly distributed throughout :a given volume. However, if the upward deilection of the discharge is caused by the application of a. transverse magnetic eld, the moving negative electrons will be deilected upwardly to form the upper boundary surface of the discharge, thus leaving the remainder of the ionized gas with a positive space charge.' Such a negatively charged'electron layer is indicated bythe electrona ill. III and i, and the positive space charge region by positive ions ils, III and Ill. Since an electrostatic attractive force exists between the positively and negatively charged layers, the upwarld defiection of the moving electrons ill, il! and i by the magnetic held will drag the positive ions- III, I" and |81 upwardly with them by electrostatic attraction, and the discharge path as a whole will be magnetically The upwardly deflected discharge will be pressed against the underside of the pins III, III and III and the deflected electrons which strike the pins will tend to give the pins a nmtive charge. In the case of an arc-splitting pin o! conventional solid construction. as is indicated by pin Ill in Fig. 2. the negative charge will tend to repel other electrons and a negative charge will be accumulated thereon as indicated by minus signs. 'Ihe negative electron layer oi' the magnetically deflected discharge is represented in l'ig. 2 by electrons I, Island |42, and the positive space charge by positive ions I, I and Ml. The transverse magnetic field acting on the moving electrons I, III- and il! in the electron layer gives them a magnetically derived denecting force tending to decct them upwardly. However, the negative charge on pin ill sets up an electrostatic repelling force which is indicated by the arrows I and |41, while the positive space charge layer sets up an electrostatic attracting force which is indicated by the arrows l and I". As a result of the above factors, the magnetic defiecting force is balanced by these electrostatic forces, and no more electrons are deflected into the plate Ill. The discharge as a whole. however, continues to rise and tends to pass either upwardly and around each pin or a hot cathode spot lll may develop on the surface of the pin, so that the discharge current passes directly through the pin ill and from hot spot Ill and forms the intermediate arc lli between it and an adjacent pin.

By modifying the arc-splitting pin to include a deionizing structure like that depicted for pin III, and by using this deionizing structure in conjunction with a magnetic neld, it is possible to trap or strip more electrons from the ionized discharge and so deionise the discharge. The means by which the modified pin Ill assists the magnetic deionizing action can be seen by referring to Fig. 3. At first it is to be noted that the same electrostatic forces that existed for pin l" of ll'ig. 2 also exist momentarily for pin lil of Fig. 3. However, pin lil is provided with pockets recessed into its imderside, and orientation of the pockets, discharge and magnetic field is so adapted as to deflect the discharge into the pockets. Becau'".l of this, the electron layer of electrons |52, Ill, I and lll can be deflected through the openings Il! in the pin III so that some of the electrons III and Ill are within the outer surface of the pin Iii. By comparing the electrostatic forces actingon the electron III in Fig. 3 with the electrostatic forces acting on the electron lli of Fig. 2, two things will be noted. iirst, that since the electron I" is inside the pin iii, 4the negative charge on the pin III cannot electrostatically repel it toward the positive space charge layer of positive ions llt, Il'l, I Il and III. and second, that the metal structure of the pin III will shield the electrons il! and I from the electrostatic attractive force of the positive space charge layer containing positive ions Ill and lll. As in Fig. 2, the electrostatic forces acting ontheelectronlayerinlig. 3arealsoshownby the arrows. It will be observed that there are no arrows representing electrostatic forces acting on the electrons within the hollowed out pin III. Since the electrostatic forces which would normally oppose the magnetically derived upward deflecting forces acting on the moving electrons Il! and its has been thus decreased or removed. the magnetic field can easily deiiect the electrons III and ill, etc., through the screen lil and into the more perfectly shielded pockets I Ila, Illib, ilc and ind of the deionizing structure included within the arc-splitting pin and thus will be able to more effectively trap or strip electrons from-the ionized arc discharge, and hence improve the dionization action of any circuit breaker in which it is used.

In general, the continued action of the magnetic field acting on the discharge will tend to ldeflect the discharge upwardly and between the arc-splitting pins iii, ill and Il! of Fig. l, and the pins will split the arc up into smaller arcs. such as arc ill and arc IIIA, as shown. It will be observed that once `the arc establishes itself between two of the pins. as in the case of pins i Il and lli and pins lli and H2, for example, the current of the arc discharge can flow by metallic conduction through the metal of the pin ill, so that the arc current ilows around the shielded pockets and the magnetic deionizing structure recessed into the pin lil. Once the arc has split around a pin (for example, pin iii of ll'igs. l and. 3), the magnetic stripping action of the deionizing structure within the pin is no longer operative, and the conventional theory of operation of the arc-splitting pin applies.

From the foregoing explanation of the action of the magnetically controlled deionialng structure, it will be evident that it would not be suiiicient to merely deflect the arc discharge against the pin iii of Fig. 3 by purely mechanical means, such as an air blast or air convection currents. If an air blast were used to blow the arc discharge against the pin I Il, it will be noted that the separation of the charged particles of the discharge into a negative electron layer and a positively charged space region would not exist. Further. any electrons, such as ill and ill, which had been blown into the pin ill through the openings III, would not be deflected up into the shielded pockets Ilia, Illb` Iflc and Illd. but would continue to move to the left and out of the partially shielded region inside the pin iii. However, when a magnetic field is used for deiiecting the discharge, such electrons as il! and i would be curved into the shielded pockets I2lb and ifld and thus stripped from the discharge.

Figs. 5 and 8 show a construction for prcvidina the magnetic deionizing surface of an arc splitting pin. The arc splitting pin Ill (Fig. 5) has been hollowed out and has a side portion cut oil' to provide for a shielded pocket, substantially as shown. 'I'he number of shielded pockets in the deionizinz surface can be increased by using conductively interconnected metallic plates to form the cellular structure III `(Ilig. 8) which is inserted in the hollow pin l as shown. Holes lllmaybeplacedinthctopofthepin Illtovent the gases out of the pockets when they are expanded by the heating effects of the ionized arc discharge being magnetically denected against the deionizing surface in the trapping member of the pin.

Fig. 'I shows a modined form oi arc splitting pin |60. The conductive shielded pockets for the delonizing surface of the trapping member are formed by the conductive plates |63, |64 and |65,

being spaced some appropriate distance and joined at the ends so as to form a conductive unit. If a single pocket is desired, the plate |64 could be omitted. The top of the pockets may be left open for venting purposes without destroying the effectiveness of the deionizing pocket providing the spacing of the plates and their width is such as to give a narrow and deep-slot so that any electron entering the pocket will be curved by the magnetic field into the sides of the plates before it can reach the top opening. In lieu of deepening the pocket. of course, the vent openins' may be restricted.

Fig. 8 shows a conventional arrangement for the use oi' arc splitting pins in a magnetic arc blow-out chute. The blow-out chute |10 contains an array of arc splitting pins |1| similar to the one shown at |60 in Fig. 5. The circuit breaker contacts |12 and |13 break the circuit in the conventional manner and thereby form the ionized arc discharge |14 through the gaseous medium. An electro-magnet |15 applies a magnetic field across the arc chute |10 in the usual manner.

In the operation of the deionizing surfaces built into the pins, when an electrical discharge through an ionizable medium is formed, such as |14 in Fig. 8, the arc discharge path |14 is magnetically deflected upward into the blow-out chute |10. In this action it is pressed against the deionizing surface on the underside of each pin by the magnetic field, and moving charged particles in the arc discharge aredefiected or curved into the confines of the conductive shielded pockets, thus stripping electrons from the ionized are discharge and thereby deionizing it.

- Several modified forms of the structure embodying my invention have been illustrated and described in order to show that the invention is not limited to any specific structure and I intend no limitations other than those imposed by the appended claims.

What I claim is:

l. In a circuit breaker including separable contacts which on opening create an electric arc discharge through an ionizable medium, means for creating a magnetic field across said arc discharge and at least one arc splitting element within said field arranged transverse to the arc discharge path and so positioned in space relative to the arc discharge formed between the separable contacts as to divide the deflected arc discharge,

said arc-splitting element being constructed to enclose a deionizing structure adapted to arrest particles of the discharge which are magnetically deflected into said structure, said element being formed of conductive material and having at least one open ended pocket in a side thereof constructed of conductive material conductively joined to said element, the joining of the parts of said modified arc splitting element being such as to form an electrical connection of conductive material having substantially no impedance and said magnetic field being adapted to deflect the discharge toward an opening of said pocket in the element.

2. In a circuit breaker including'separable contacts which on opening create an electric arc discharge through an ionizable medium, means for creating a magnetic field across said arc discharge and at least one arc splitting element within said field arranged transverse to the arc discharge path and so positioned in space relative to the arc discharge formed between the separable contacts as to divide the deflected arc discharge, said arc-splitting element being integrally formed of conductive material and comprising at least two conductive plates substantially parallel to one another, said plates being oonductively joined together to form at least one deep and narrow open ended pocket, the joining of the parts of said modified arc splitting element being such as to form an electrical connection of conductive material having substantially no impedance, and said magnetic field being adapted to defiect the discharge toward an opening in said pocket.

3. In a circuit breaker including separable contacts which on opening create an electric arc discharge through an ionizable medium, means for creating a magnetic field across said arc discharge and an arc-splitting element within said field arranged transverse to the are discharge path and so positioned in space relative to the arc discharge formed between the separable contacts as to divide the deflected arc discharge, said arc-splitting element. being formed of conductive material and constructed to embody a deionizing structure adapted to arrest particles of the discharge which are magnetically deflected into said structure by having at least one pocket inside of said element constructed of conductive material conductively joined to said element, the joining of the parts of said modified arc splitting element being such as to form an electrical connection of substantially no impedance at least one aperture through the side of the element and means for venting said pocket, said magnetic field being adapted to defiect the discharge toward an aperture in said element and into said pocket.

4. In a circuit breaker including separable contacts which on opening create an electric arc discharge through an ionizable medium, means for creating a magnetic field across said arc discharge and an arc-splitting element Within said field arranged transverse to the arc discharge path and so positioned in space relative to the arc discharge formed between the separable contacts as to divide the deflected arc discharge, 'said arc-splitting element being of conductive material and constructed to enclose a deionizing structure composed of conductive material conductively joined to said element by an electrical connection of substantially no impedance and being adapted to arrest particles of the discharge which are magnetically deflected into said structure by having a plurality of pockets inside of said element with at least one connecting aperture through the side of the element, said magnetic field being adapted to deflect the discharge toward said aperture.

5. In a circuit breaker including separable contacts which on opening create an electric arc discharge, means for creating a magnetic field I fied arc splitting element being such as to form an electrical connection of substantially no impedance said magnetic field being adapted to deilect the discharge against said side of the element.

6. In a circuit breaker including separable contacts which on opening create an electric arc discharge through an ionizable mediummeans for creating a magnetic field across said arc discharge. and an arc splitting element within said field arranged transverse to the arc discharge path and so positioned in space relative to the arc discharge formed between the separable contacts as to divide the deflected arc discharge, a trapping device formed within the element, said trapping device including at least one electrically shielded pocket constructed of conductive material and conductively joined to said element by an electrical connection of substantially no impedance and being adapted to arrest charged particles which are magnetically curved into said pocket, said element being constructed to have at least one aperture through the side of said element which faces the path of said arc discharge, said magnetic ileld being adapted to deiiect the discharge toward said aperture, whereby charged particles are magnetically curved into said trapping device in the element to magnetically strip charged particles from the arc discharge and deionize the arc discharge.

7. In a circuit breaker including separable contacts which on opening create an electric arc discharge through an ionizable medium, means for creating a magnetic field across said arc discharge. and a metallic arc splitting element within said field having surfaces arranged transverse to the arc discharge path and soA positioned in space relative to the arc discharge formed between the separable contacts as to divide the deilected arc discharge, said arc splitting element containing a trapping device between said surfaces, said trapping device including at least one pocket bounded by at least two conductive surfaces substantially parallel to one another and substantially normal to the path of the discharge, said conductive surfaces being conductively joined together and to said arc splitting .element the joining of the parts of said modified arc splitting element being such as to form an electrical connection of substantially no impedance, and said magnetic iield being adapted to deectthe discharge toward said pocket, whereby charged particles are magnetically stripped from the arc discharge, curved into said trapping device and trapped therein.

8. An arc splitting element so positioned in space as to divide a magnetically deflected arc discharge and so modied internally as to include at least one pocket therein, said pocket being defined by a boundary surface of conductive material, at least one opening in said arc splitting element providing a path into said pocket, and means for subdividing the pocket opening by at least one conductive member conductively joined to said element by an electrical connection of conductive material having substantially no impedance, thereby creating a structure whereby a charged particle magnetically curved into and trapped within said arc splitting element is substantially shielded from electrostatic fields external to said arc splitting element.

9. An arc splitting element adapted to divide a magnetically deected arc discharge and modified internally so as to include at least one pocket substantially bounded by conductive material, at least one opening in the side of said arc splitting element providing a path into said pocket,

and at least one metallic plate within said pocket adapted to subdivide said pocket and said opening, said plate being conductively joined to said arc splitting element by an electrical connection of substantially no impedance, thereby creating a structure wherebyf a charged particle trapped within the resulting shielded region of said arc splitting element is substantially shielded from electrostatic fields external to said arc-splitting element. t

l0. An arc-splitting element so positioned in space as to divide a magnetically deflected arc discharge and constructed to enclose a shielded conductive deionizing structure, said element being formed of conductive material to have a substantially cylindrical shape, said structure including at least one pocket formed of the conductive material of said element conductively joined to said arc splitting element by an electrical connection of conductive material having substantially no impedance, and including at least one opening through the surface of 4said element forming a path Vinto said pocket, thereby creating an arrangement which facilitates the magnetic deection of moving charged particles into the shielded region of said structure wherein said trapped charged particles are substantially shielded from electrostatic elds external to said arc splitting element.

l1. An arc splitting element adapted to divide a magnetically deflected arc discharge and constructed to enclose a shielded conductive deionizing structure, said element being formed of conductive material to have a substantially cylindrical shape, said element being hollowed out to form at least one comparatively large substantially cylindrical pocket, said element having at least one opening through a surface thereof providing a path into said large pocket, a plurality of metallic plates conductively joined to said element Within said large pocket adapted to substantially subdivide said large pocket into a plurality of small pockets, said plates being conductively connected to said arc splitting element by electrical connections of substantially no impedance, and said smaller pockets each having at least one opening through the plates connecting to said large pocket, thereby creating a, structure which facilitates the magnetic deflection of moving charged particles into said shielded pockets wherein said trapped charged particles are substantially shielded from electrostatic fields external to said arc splitting element.

l2. In combination with a circuit breaker having separable contacts which on opening create an electric arc discharge through an ionizable medium, means for creating a magnetic field across said arc discharge and an arc splitting element within said eld transverse to the arc discharge path arranged to arrest particles of the discharge and so positioned in space relative to the arc discharge formed between the separable contacts as to divide the deflected arc discharge, said element having a trapping device therein with at least one deionizing surface including at least two conductive plates substantially parallel to one another and normal to the path of the dischargel, 'said plates being conductively joined together and to said element through an electrical connection of substantially zero impedance and said magnetic field being adapted to deflect the discharge against said surface.

HOWARD M. STROBEL. 

